每只救生筏的构造，应能经受在一切海况下暴露漂浮（）天。
A.15
B.30
C.50
D.60
参考答案：B
一次函数y=2x-2的图像不经过的象限是（ ）
A．第一象限
B．第二象限
C．第三象限
D．第四象限
When a firm is earning positive economic profits in a monopolistic competitive market, what will most likely occur（）
A. New firms will enter driving down the economic profits to zero.
B. Losses will occur in the short run.
C. Price takers will be over run by price searchers.
